The sanitation industry typically employs one of several types of solutions for cleaning and sanitizing washrooms and toilet areas. These solutions include: a quaternary ammonium salt-based formula (typically referred to as ‘Quats’); a sodium hypochlorite based formulation (typically referred to as ‘bleach’), acidic cleaners; caustic or basic cleaners; and, hydrogen peroxide-based formulas.
The most common types of solutions for washroom cleaning and sanitizing are Quats, which are effective and widely used. However, these formulations are quite toxic and can adversely affect the bacteria used in modern water treatment systems.
There are various hydrogen peroxide-based cleaning solutions for sanitizing and controlling odour in washrooms and toilet areas, such as described in U.S. Pat. No. 5,611,088 to Almon. Almon discloses a sanitary system where an electro cell is mounted in the toilet tank reservoir, which causes a portion of the water in the reservoir to be converted to hydrogen peroxide. The hydrogen peroxide is then introduced to the toilet bowl where it deodorizes and sanitizes all exposed surfaces. However, Almon requires that the toilet being sanitized has a reservoir where the electrode can be mounted, and this is not the case for all toilets and urinals. In addition, hydrogen peroxide works as a sanitizer but is not a cleaner.
U.S. Pat. No. 6,346,279 to Rochon discloses a hydrogen peroxide solution with a pH of between 1 and 3, which is used in conjunction with a phosphorus-based acid. This method is effective, however, the low pH of the solution can cause severe corrosion in the washroom plumbing and phosphoros acid compounds can be somewhat harmful to the environment.
U.S. Pat. No. 6,387,321 to McGill discloses a hydrogen peroxide solution used in conjunction with a sodium hypochlorite compound for controlling toilet odour. As with the other hydrogen peroxide based solutions, this is effective for sanitizing washrooms, however, sodium hypochlorite, commonly known as bleach, is a harsh chemical and is not environmentally friendly.
U.S. Pat. No. 7,169,237 to Wang, et al., discloses a formulation using a catalyzed phosphoric acid and a stannate stabilizer. The inherent problems with this cleaning solution are that it puts phosphoric acid into the environment, which can acidify soils and contribute to water pollution, and it exacerbates corrosion problems in washroom plumbing, which is an issue for all acidic cleaning solutions.
Accordingly, there is a need for a washroom cleaning and sanitizing solution that works with all types of toilets and urinals, is environmentally friendly, inhibits corrosion in washroom plumbing, and has pH of 7-9.
The solution detailed in this application was a significant challenge for the applicant because of the unusual and contradicting factors that had to be considered when developing an effective hydrogen peroxide solution that cleans, sanitizes, deodorizes and limits the formation of mineral scale. It is well known that:                Iron and copper are decomposition catalysts for hydrogen peroxide;        Both nitrogen-based (such as EDTA or ethylenediaminetetraacetic acid) and phosphorus-based (such as phosphoric acid) chelating agents have more affinity to copper than calcium or magnesium. This means that chelation is necessary for hydrogen peroxide stability but is corrosive to copper and brass. In the presence of copper, chelating agents tend to react with copper and not work as a scale inhibitor;        Unlike metals such as aluminum, copper oxide does not form a strong copper oxide film on the interior pipe walls that would protect the rest of the copper plumbing from corrosion;        Hydrogen peroxide is more stable at higher concentration and even when it is diluted with water of the highest purity, it is less stable than the concentrated product; and        Hydrogen peroxide is more stable at a pH below 4-4.5 without stabilizers.        
It is therefore quite a challenge to make a cleaning and sanitizing solution that has 0.5%-5% hydrogen peroxide, that is neutral (pH of 7-9), that is stable during storage and that is non-corrosive to brass and copper pipes.